Stoptech BBK Disk offsets front and rear?

[CB72]

I'm contemplating using a front Stoptech BBK on the rear of my NSX.
The reason beeing that it would give me a good F/R bias with my front Porsche 993 turbo calipers.
While I know that the center hole is a different size, I don't know if the disks have the same offset?
BTW there are no kits available on the market today and the leadtime is a 40 to 60days...

 

[BBVNSX]

Hello John,

It would be a long, long shot for them to work... not only disks on the equation... also brackets, and calipers... calipers are the same model (ST40)... but there is one area of the caliper that is machined to each aplication so that it works with the needed ofset (having in mind disk and bracket)... This means that even if the disks are the same ofset, it doesn't mean it will work.

Also you are increasing your piston area when compared to OEM... so theoretically you will need more brake pedal travel to achieve the same amount of brake... so it is a good idea to think it well... not saying it will not work... but you may find it won't after spending the money...

P.S. Stoptech have technical drawings/templates on their website... so probably it is a good start...

I'm contemplating using a front Stoptech BBK on the rear of my NSX.
The reason beeing that it would give me a good F/R bias with my front Porsche 993 turbo calipers.
While I know that the center hole is a different size, I don't know if the disks have the same offset?
BTW there are no kits available on the market today and the leadtime is a 40 to 60days...

 

[CB72]

Hello John,

It would be a long, long shot for them to work... not only disks on the equation... also brackets, and calipers... calipers are the same model (ST40)... but there is one area of the caliper that is machined to each aplication so that it works with the needed ofset (having in mind disk and bracket)... This means that even if the disks are the same ofset, it doesn't mean it will work.

Also you are increasing your piston area when compared to OEM... so theoretically you will need more brake pedal travel to achieve the same amount of brake... so it is a good idea to think it well... not saying it will not work... but you may find it won't after spending the money...

P.S. Stoptech have technical drawings/templates on their website... so probably it is a good start...

Thanks Bruno.
I had no idea the calipers could be different between the front and the rear at least from an offset and "Pl" dimension as shown in your pictures...
No wonder you can't get them off the shelf!
This leaves me with two options: eitheir go with the rear Brembo kit or the Tarox kit.
The Brembo would be my favorite despite the price as I would get the equivalent of the F40 front and Lotus rear caliper system, a configuration that was used by some racers in the past!
Porsche GT3 drivers: watch your rear mirrors!

 

[RYU]

BTW there are no kits available on the market today and the leadtime is a 40 to 60days...

Just to clarify, are you saying Stoptech is out of stock on the NSX kits?

 

[MotorMouth93]

What piston sizes are you looking for? I've done a decent amount of research into retrofitting calipers from other cars lately. My current side project is retrofitting 996 calipers in the front (same piston sizes as NA1 and 986 but works with thicker rotors) then figuring out a rear setup, possibly using 986 front calipers for 50/50 piston bias then adjusting rotor sizes to get to about 53% front bias like the NA2, or taking the easy way out and sourcing NA2 rear calipers to not worry about the parking brake.

Porsche 993TT "big red" calipers have 44/36mm pistons, using something like 986 boxster front calipers in the rear (40/36mm pistons) would put you very close to the NA2 brake piston bias then you could play with rotor sizes to fine tune from there. 986 calipers are also very cheap.

 

[RYU]

I also have 4 pairs of various calipers as well. I have Stoptechs, Brembos, and Porsche (Brembo). None of them are NSX native but I collected them in hopes of an NSX application. LMK if I can help. They're just sitting in storage now.

 

[CB72]

What piston sizes are you looking for? I've done a decent amount of research into retrofitting calipers from other cars lately. My current side project is retrofitting 996 calipers in the front (same piston sizes as NA1 and 986 but works with thicker rotors) then figuring out a rear setup, possibly using 986 front calipers for 50/50 piston bias then adjusting rotor sizes to get to about 53% front bias like the NA2, or taking the easy way out and sourcing NA2 rear calipers to not worry about the parking brake.

Porsche 993TT "big red" calipers have 44/36mm pistons, using something like 986 boxster front calipers in the rear (40/36mm pistons) would put you very close to the NA2 brake piston bias then you could play with rotor sizes to fine tune from there. 986 calipers are also very cheap.

You must have read my notes!
The 986 Boxster front calipers are the right size for the job.
I was trying to get the "Pl" and offset numbers but couldn't find them?
They would possibly just fit on the 302 mm NA2 disks that I'm currently running with APracing CP7611's.
I made contact with a company in Australia that have used them for other Honda's but they didn't have the data?
I'm not keen on buying second hand calipers just to get the numbers...

 

[CB72]

Just to clarify, are you saying Stoptech is out of stock on the NSX kits?

Yes sir!
Since they've been acquired by Centric they must have been drowned in a bigger pool...
Lead time is quote at 40 to 60 days!

 

[CB72]

I also have 4 pairs of various calipers as well. I have Stoptechs, Brembos, and Porsche (Brembo). None of them are NSX native but I collected them in hopes of an NSX application. LMK if I can help. They're just sitting in storage now.

Great!
It would be nice to know the piston sizes of what you have so as the sizes of the OEM disks they were used for?

 

[RYU]

Great!
It would be nice to know the piston sizes of what you have so as the sizes of the OEM disks they were used for?

One set is the 986 Boxer S front and rear calipers only. One is a front pair of Stoptechs for an 1st gen Acura RSX which I meant to retrofit into the NSX someday. I have a full set of Brembos that I recently uninstalled took off my NSX. It has F430 (or 360 Modena) front "lotus" calipers and the Comptech Brembo "lotus" rears. This set actually matches up quite well at approx 60% bias. I also have a pair of new rotors off a A class AMG sedan. I have a few others I can't recall. It was an obsession for me at one point to build my own BBK but i'm back to stock NA2 hysterically enough..

 

[MotorMouth93]

You must have read my notes!
The 986 Boxster front calipers are the right size for the job.
I was trying to get the "Pl" and offset numbers but couldn't find them?
They would possibly just fit on the 302 mm NA2 disks that I'm currently running with APracing CP7611's.
I made contact with a company in Australia that have used them for other Honda's but they didn't have the data?
I'm not keen on buying second hand calipers just to get the numbers...

Edit: I now see that I misread your post and that you just talking about buying used calipers to take measurements before buying new. I have some 986 calipers already and can take measurements if you need them.

Fair enough, but it's worth mentioning that used calipers can be restored to like-new just by replacing the seals, they are aluminum so rust and corrosion isn't really a concern, and they can also be painted or powder coated to match your front calipers. OEM Brembo/Porsche seal kits run about $50/caliper. https://www.fcpeuro.com/products/po...pair-kit-centric-genuine-porsche-kit-14337009

This is an old 996 caliper I did.

 

[RYU]

^^ beautiful

 

[CB72]

Edit: I now see that I misread your post and that you just talking about buying used calipers to take measurements before buying new. I have some 986 calipers already and can take measurements if you need them.

Fair enough, but it's worth mentioning that used calipers can be restored to like-new just by replacing the seals, they are aluminum so rust and corrosion isn't really a concern, and they can also be painted or powder coated to match your front calipers. OEM Brembo/Porsche seal kits run about $50/caliper. https://www.fcpeuro.com/products/po...pair-kit-centric-genuine-porsche-kit-14337009

This is an old 996 caliper I did.

Thanks for the proposal!
One issue remains which is the size of the disks that can be used with these calipers?
With my current setup, I've managed to explode the Centric/Stoptech NA2 size rear disk at the end of a straight at around 120 mph.
The RS14 pads that I use also disintegrate after a few track days.
Larger disks are clearly a must.
328x28 seems the minimum size to me?
Would you please just provide me with the offset and Pl measurement ( top of pad to base of caliper) to at least determine feasability.
Thanks
John

 

[MotorMouth93]

For that rotor thickness you could use the 996/Boxster S calipers which have the same piston sizes as the regular Boxster calipers but are made to work with thicker 28mm rotors instead of 24mm like the Boxster uses and larger brake pads. Some of the 996 guys run these calipers with 340mm rotors and spacers (stock rotors are 318mm) so 328x28 should fit just fine. I know guys have also put these on E39 and E46 BMWs using rotors in that size range as well.

I have a set of these too so I'll get the measurements tonight.

 

[MotorMouth93]

The offset from the center of the mounting holes to the center of the rotor is roughly 53mm and it uses radial mounting holes.

And at the risk of sounding dense, I'm still not sure what you mean by Pl measurement and google isn't helping, do you have a diagram or something showing what to measure?

 

[CB72]

The offset from the center of the mounting holes to the center of the rotor is roughly 53mm and it uses radial mounting holes.

And at the risk of sounding dense, I'm still not sure what you mean by Pl measurement and google isn't helping, do you have a diagram or something showing what to measure?

It must be an APracing term.
Here's a drawing with all the data:
https://apracing.com/cdn/drawings/cp9440-1cd-iss4.pdf
I will also need the distance between the two main bolts.
As I have the Brembo parking brake, I'd like to stick to 328 mm rotors.
Another point to check is the pad depth as it's difficult to find rotors that take more than 50 mm pads...
I had the issue with my front calipers that have 60 mm deep pads!
Edit: look no further the pad depth is 60 mm
https://www.pagidracing.com/en/prod...ing-brake-pads/shape-detail/s/shape-2405.html

 

[MotorMouth93]

Ah yeah the pads are pretty big.

Pl is 70mm, mount hole spacing is 130mm.

 

[CB72]

These would be a good fit for the front brakes.
My Porsche/Brembo "F40" calipers have similar dimensions with an offset of 55 mm, Pl of 60 to 62 mm and bolting holes at 130 mm.
Titanium Dave made some special hats for me to take Brembo 328x32 slotted disks to work with these.
The Brembo P/N are 09.9227.12/22.
The annulus is 64 mm to take the Porsche pads.
I'll send you a picture later on so as a sketch of the bracket needed if you are interested.